MAIN BEARINGS FAILURE, MUST CHANGE

With regard to the previous main bearing thread:

In a nutshell what I believe to be weak links:
1. Improper running clearance as a result of sloppy case bore
tolerance.

2. Axial crankshaft bore misalignment as a result of sloppy tolerance
control.

3. Using a single point, contra rotating, axial mount balance
assembly. Such an assembly induces a "Rocking Couple" which
causes the crankshaft to oscillate as opposed to rotate.


All of the above exaggerated via excessive rpm and / or loads.


Sincerely,
Dale

Click to expand...

i'm sure you'll find a piece from dale about the inner race, feel free to supply it. as for the bearings yes they are good enough when all is well but they fail because they are only marginally good enough to do the job. you sail close to the wind and you get bitten now and again. i differentiate between service life and being far more than is required to do the job. call it bulletproof if you like. clearly the mains are unable to cope with any ailments that we have yet to confirm 100%. the proof is in the pudding.

if you accept that it's running the same mains as when the engine was originally conceived then yes, i stand by my statement that they didn't plan it as a 650. and even if they did they haven't beefed up the botoom end, the japs would have done. explain to me the photo of all the mains in weeds photo gallery? the husey's are just about the smallest.

i'm not really sure where you're coming from simon because you talked of crank issues only yesterday and on the last page?

anyway, what was your point about the inner race?

regards

Taffy

Bingo! A lightweight engine designed around a 92X73 B&S originally producing 49HP in off road use now having problems at close to 70HP on tarmac at 100x80. Since a redesign isn't in the cards, the creativity of guys like Dale, JBS, etc. will eventually find a way around it. Will be interesting to follow.

message to ausberg,
one thing i didn't test test with mine,after the main bearing failure was the alignment of the crank.
it would have been nice to know if the crank keeps it alignment true or over time does it go out.
i see enginehardware puts a weld on the end of crank pin to crank to make sure nothing will move,i wish i would done the same thing with mine now.
a mate of mine was replacing the crank pin in his wr450 at the same time i doing the same in mine,the crank pin was tighter fit in the wr,just got me thinking, it might be possible for the alignment to go out.
is the alignment in your crank orignal as it came out ausberg,could be worth knowing for everyone if its lost its trueness.
on the subject of end float,i made up a jig that goes over the flywheel to test the crank end float,ive been testing the end float at the end of each ride with the bike still at operating temp.i'm getting .1mm end float.the engine was assembled with .2mm cold.
the biggest test will be after a stinking hot hot day.
all is good so far.
..weed..

weed

looking from an engineering perspective i do know that there is a certain pressure in tons that beyond which the sheer pressure causes 'spread', in other words there is too much force and the metals move away. i don't know where the numbers are for that.

i can only recount the tail of a bloke up here in the Uk who decided to be a ducati engineer and tuned the balls off an old 900ss air-cooled. this was his speciality...

he ignored the procedures set down and wowed everyone with the supa-dupa extra tonnage. however his cranks all failed and he went out of business.

do you know what the pressure ratings are from husaberg and for that yam? measurements? it would be a good one for the doc.

regards

Taffy

popup said:

message to ausberg,
one thing i didn't test test with mine,after the main bearing failure was the alignment of the crank.
it would have been nice to know if the crank keeps it alignment true or over time does it go out.
i see enginehardware puts a weld on the end of crank pin to crank to make sure nothing will move,i wish i would done the same thing with mine now.
a mate of mine was replacing the crank pin in his wr450 at the same time i doing the same in mine,the crank pin was tighter fit in the wr,just got me thinking, it might be possible for the alignment to go out.
is the alignment in your crank orignal as it came out ausberg,could be worth knowing for everyone if its lost its trueness.
on the subject of end float,i made up a jig that goes over the flywheel to test the crank end float,ive been testing the end float at the end of each ride with the bike still at operating temp.i'm getting .1mm end float.the engine was assembled with .2mm cold.
the biggest test will be after a stinking hot hot day.
all is good so far.
..weed..

Click to expand...

weed,
unfortunately my crank has already been split- so checking alignment is now impossible.
However, prior to splitting I did a quick check of webs for parallel/spreading between big end and 180 degrees opposite- all was fine.
Unfortunately I did not check it to see if there was any movement between left and right webs about the big end pin.

I know what you mean about tightness of press fit- mine came apart easier than expected,and its interesting to note that a lot of the RFS guys with big cube strokers also resort to welding to maintain crank alignment.

Good to see yours is up and running, end float specs are interesting.

Keep us updated on how its performing- I think you are the only guy on this site who opted for that style main on the primary side- what did you select for ign side main ?
And how are you finding it minus balancer? did you balance to any other factor or leave as is??
Enquiring minds need to know

BTW, there has been one of the more interesting/informative subjects I've seen discussed on this site- even if a bit controversial. But its good to see all the opinions,suggestions, fixes etc out there, regardless of what we personally deem to be right or wrong :wink:

And I think its a long way from finished yet........... :?: :lol:

Cheers,
ausberg

ausberg

enginehardwear and takis have this 20mm wide bearing. perhaps i've missed someone else?

you have a PM?

regards

Taffy

Taffy said:

they are only marginally good enough to do the job.

Click to expand...

.

Then provide the figures upon which you base that statement Taffy.

Even through my rudimentary calculations I have shown that the bearings are more than up to the job of taking peak crankshaft acceleration loads.

I hasten to add that nobody has come back and questioned those figures I've provided. If they did I'd be more happy to accept a contrary argument or discussion because then it would be based more upon fact.

Taffy said:

call it bulletproof if you like

Click to expand...

.

Taffy said:

i stand by my statement that they didn't plan it as a 650.

Click to expand...

Taffy said:

the husey's are just about the smallest

Click to expand...

These bikes were never designed to be bulletproof in the way you guys seem to be expecting them to be.

Well, you clearly have some ability to read the minds of inside the factory when they were designing the new crop of post 2001 engines.

And Husaberg and when they were Husqvarna lead the way in 4-stroke competition engines. Actually they were 4-stroke competition engines. They were also about always pushing the envelope.

Taffy said:

i'm not really sure where you're coming from simon because you talked of crank issues only yesterday and on the last page?

Click to expand...

Yes, I have talked of crank issues, hut I have never said I think the crank is the problem. And I have never said I believe that the problem is caused by crank flex.

I have very clearly stated that I believe the main problem to be caused by harmonics and that is a very different thing from the crank.

Taffy said:

anyway, what was your point about the inner race?

Click to expand...

Too tight fit on the crankshaft can change the shape and running surface of the inner race. It has happened but by and large I don't think it is the issue either. It is just something that again needs to be eliminated.

All the best,
Simon

popup said:

ive been testing the end float at the end of each ride with the bike still at operating temp.i'm getting .1mm end float.the engine was assembled with .2mm cold.

Click to expand...

Thank you weed, that is good to know.

Simon

Taffy said:

enginehardwear and takis have this 20mm wide bearing. perhaps i've missed someone else?

Click to expand...

Yes, since about 2001 :wink:

And you need to remove the counterbalancer of course and it givse you the option of installing a self-aligning bearing which has a minimum width of 20mm or the spherical roller bearing weed is trying which also has a minimum width of 20mm. Obviously some of these also have reduced limiting speeds that may or may not be suitable for what you're up to.

Simon

Taffy said:

ausberg

enginehardwear and takis have this 20mm wide bearing. perhaps i've missed someone else?

you have a PM?

regards

Taffy

Click to expand...

Taffy,
weed has been a brave man and opted for the 20mm wide self aligning spherical roller
RHP 22206

EngineHardware uses a 20mm wide cylindrical roller- SKF NJ 2206

Not sure about Takis/Bergo- I think also the 20mm wide cylindrical roller ??

I think weed is the only one out there using the self aligning spherical?? Thats why some long term feedback would be nice

quite right. i'll shut up now! forgot that weed had gone to the spherical.

regards

Taffy

Taffy said:

looking from an engineering perspective i do know that there is a certain pressure in tons that beyond which the sheer pressure causes 'spread', in other words there is too much force and the metals move away. i don't know where the numbers are for that.

Click to expand...

That is going to depend on a number of factors.

However, you are looking in the wrong direction.

Peak load on the crankshaft is upwards -when the piston gets to TDC on the exhaust stroke. It is not, as many wrongly assume, on the combustion stroke.

I have given you a rdumentary calculation of what I think is the max. forces at 9000rpm on a 2001 650. This force will reduce on shorter stroke engines and slightly reduce with longer conrod for the given rpm.

Cheerio,
Simon

i'm on about pressing the crank together simon.

regards

Taffy

Taffy said:

i'm on about pressing the crank together simon.

Click to expand...

So you're talking about the elastic limit of the materials, then?

I what sense? The material, i.e. crank web, going beyond its elastic limit when you press in the big end pin?

I doubt that is the issue but if you confirm the exact material of the crank web, it'll be fairly straight forward to find the Young's modulus.

All the best,
Simon

there is a certain pressure, recommended by the factories at which it was advised that you pressed the crank of a duke together. as power increased the temptation was to build a slightly larger big end and use more tonnage to press it all together. what the guy didn't know was that at a certain point the join became weaker and the cranks 'went'. now this is 20 years plus ago and i can't recall a lot more here.

i can even tell you what he called his business. it was tommasso tuning and the guy i think, came from bedford and he was getting massive RW numbers but he was doing it the quick way and using his customers as guinnea pigs. he had a few cranks go west and he closed up, total operation probably 24 months total.

i'm only reacting to ausberg/weed's chat so if you could just get off my phucking back as it's hard to breath....

as for harmonics not being the crank yeh....whatever you say...

regards

Taffy

Taffy said:

i'm only reacting to ausberg/weed's chat so if you could just get off my phucking back as it's hard to breath....

Click to expand...

Taffy, you post a remark on a public forum, what esle can you expect than someone asking for clarity..... :wink:

Why? Because there is so much conjecture and so many vague, unclear and quite frankly misleading comments made without basis, engineering or otherwise, that I'm simply trying to get some clarity about what is being talked about and referred to.

You can't blame a man for that and I'm not going to apologise for it either.

Taffy said:

as for harmonics not being the crank yeh....whatever you say...

Click to expand...

You really don't get it do you????

If you can't get your head around the fact that the harmonics are likely to be a result of an interaction between many components, then there is simply no point continuing the discussion.

As I've clearly said before, the crank plays a part but I don't think it is the crank.

If you really need it spelling out: it means I believe that the problem is not the crank on its own. :roll:

If you guys want to continue down the road of main bearings and/or crankshaft in isolation, please be my guest.

I have nothing else to add the discussion and unless someone can come and back up what they're saying with some facts and figures , I'm done.

All the best,
Simon

Hi Simon,

What the hell I'll bang my two peneth for what it's worth, yes you are correct when you say the peak load is the throw after TDC.
Interesting thing here the Ducati's reciprocating mass was said to be the hieghtest load recorded as it passed TDC, I thought Taff might of know about that, now then I used to ride a 748SPS which you can push to around 12000 to 12500 RPM and guess what some 748SPS's suffered from main bearing failure, but on the Husaberg we are talking max around 9000RPM but do some people go beyond that thresh hold bearing in mind there is no rev limiter especially the FS boys and how long is it being held there for at high RPM.
Another point I would like to make it that it is only the left main bearing that is pressure fed with oil the right only gets what has been squirted up the bore and runs down the small oil hole, how many people suffer more right failure then left.
As for harmonics on a four stroke I think probably not on a two stroke yes as the frequency is a lot higher.

Regards

Sparks.

http://www.husaberg.org/modules/gallery ... .sized.jpg

i've put a photo into 'engine upgrade' in the owners doc from takis. it's interesting because if you recall, after i spoke to the SKF guy he said easier fit on crank and slightly harder in case. maybe this bearing was a real easy fit because i think they are somehow about to turn it and let the countersunk screws sit in the 'sunken' areas of the bearing outter race.

must be close to turning in the case?

regards

Taffy

sparks said:

but on the Husaberg we are talking max around 9000RPM but do some people go beyond that thresh hold bearing in mind there is no rev limiter especially the FS boys and how long is it being held there for at high RPM.
Another point I would like to make it that it is only the left main bearing that is pressure fed with oil the right only gets what has been squirted up the bore and runs down the small oil hole, how many people suffer more right failure then left.
As for harmonics on a four stroke I think probably not on a two stroke yes as the frequency is a lot higher.

Click to expand...

Hey sparks,

Interesting to hear your thoughts.

There are some people that do over rev their sm motors but in my experience they are ones who have come from road race 4 cylinder type backgrounds. They don't do it for long :wink:

I don't know about others who get involved in tuning these motors but I have never gotten a peak power output that lies beyond 8700rpm so beyond that it is pointless trying to rev. as power drops off rapidly. I think those who are good riders will know this and keep it in the good range.

I tried just about every engine combination possible at the time on my 01 650 including dyno testing pretty much every one of them too.

Also, what I have found and experienced was that at high sustained rpm it was most likely high top end wear that was the problem - once the counterbalancer was thrown away, that is. Then with the highest compression ratio we could muster it was bigend which we eventually solved.

It is very rare that the right hand main goes - it always seems to be the left.

As for the harmonics I understand fully your doubts.

As you may or may not be aware I've been plugging away for a few years in my shed with some harmonics stuff, particularly around differential path silencers. One thing that guides my mind towards the harmonics angle is that at certain rpm I can measure significant resonance at particular frequencies that cannot be accounted for accoustically from combustion.

This has to be coming from somewhere,it is most probably of mechanical origin and the amplitude is very significant!

By and large I think the counterbalancer is playing a much more major role in these problems than people want to admit...

All the best,
Simon

just like to clear up a couple of points.
the main bearings i ended up putting in my bike was a rollway nj2206 c4 on drive side/ntn 13 roller nj206 off orangeberg
.sorry for the bum steer.but this is what happened.
i bought a few bearings to have a look at,which were spherical nj22206/nj2206/nup206/ntn nj206/plus 2x6206 bearings to check bearing/crank alignment.
i decided i would give the spherical roller a go on the drive side with ntn nj206 on the other.
well at the time i was baby sitting kids,made a big f# up pressed the spherical roller in /had the crank pressed through the inner of the spherical, all was good until i realized i forgot to put the timing/water pump shaft in 1st.
i reckon taffy would have heard me swearing from the other side of the world!!
my little brain can't handle trying to do 2 things at once.
when i tried to pull the spherical roller off i cracked the outer(stuffed it)
i couldn't justify buying another, when i already had a nj2206 that would do the job, so thats what went in.
dan was thinking about putting a spherical roller in his at the time ,so i put the pics what i had in my gallery for him to have a look at.
i will now edit the captions so there is no further confusion.
ausberg,i did do a crank balance,i just followed the instructions from the book "tuning for speed".i believe it has been a success.i've had 2 other blokes ride my bike since the crank balance.1 bloke rides a cr500, he said said his bike vibrates more than what the berg does & i agree with him.the 2nd bloke rides a crf450 & said the vibration felt nothing out of the ordinary to him.i wish there was another 650 berg in town to compare it with.its certainly a lot better than when i was running the bike without a c/b and no crank balance.
if there is a controversy, its the way in which you decide to attach/add weight to the crank.
i will put it in my gallery what i done,but until its done probably 5000kms i cant say its bulletproof.as is i've only put 3 tanks of fuel trough it,but all looks good.
..weed..